Class for HUGE numbers?

I’m making a game at the moment that uses big numbers. The Number class works perfectly up to somewhere around 1.00x10^300. I would like to use much higher numbers though if possible.

I figure the way would be to create a new class that uses 2 numbers. One for the decimal part and another for the exponential part. Then presumably the numbers could go up to 1.00x10^(1x10^300).

Anybody know a practical way to do this? Or of another solution?

Thanks!